This chapter is from the book

While Photoshop is a great tool for a lot of tasks, most of them center around the sizing, manipulation, and processing of
digital images. While their contents may vary, all digital images are essentially the same: They are composed of pixels that
contain color and luminance information. Photoshop’s powerful features will allow you to adjust those pixels to better match
your needs.

While the destination may be the same, the path your digital images take to get inside of Photoshop will vary. Some may start
out as digital images acquired with a still camera, while others may get loaded via a scanner. You may also find yourself
turning to online resources to find specialized images. Let’s take a look at the many ways to acquire your digital images.

Digital Cameras

This book will not teach you how to use your digital camera. There are many excellent books on that subject as well as classes
offered. What we will address is how the pixels are converted, what file format you should choose to shoot your images, and
how to transfer them to your computer.

Digital Camera Technology

Shooting a photo digitally produces a less accurate image than scanning a photo shot on film and scanned with a flatbed scanner
using a high SPI setting. This is because digital cameras capture data using photosensitive electronic sensors. These sensors
record brightness levels on a per-pixel basis. However, these sensors usually are covered with a patterned color filter that
has red, green, and blue areas. While the filter attempts to capture all detail that the lens sees, it is unable to due to
its design.

The filter used is usually the Bayer filter arrangement, which contains two green pixels and one red and one blue. The Bayer
filter uses more green because the human eye has increased sensitivity to green. This filter allows the image to record the
brightness of a single primary color (red, green, or blue) as digital cameras work in the RGB color space. The RGB values
combine using the additive color theory (which we briefly discussed in Chapter 1, “Digital Imaging Fundamentals”) and form an image when viewed from a suitable distance.

Since not all traditional camera functions can be fully imitated by the computer sensors in a digital camera, the camera must
interpolate the color information of neighboring pixels. This averaging produces an anti-aliased image, which can show visible
softening. When anti-aliasing is present, hard edges are blended into one another. Sometimes this can be desirable (with low-resolution
Internet graphics where you reduce file size by limiting color). Other times, anti-aliasing can produce an undesirable softness
when you print an image. Depending on the colors in the original image, a digital camera may only capture as little as one-fourth
of the color detail. For example, if you had a scene like a desert with a great detail of red, and little green or blue, the
sensor would rely on the red areas of the filter (which only cover a fourth of the sensor face).

Am I saying to shoot film only? Of course not... I shoot both. What is important is to shoot for what you need; there are
strengths and weakness to both film and digital (as well as several stylistic decisions as well). Ultimately, film captures
a high-quality image that can be optically enlarged using the negative. However, digital can be more convenient and affordable
as you get instant feedback on the images you have just taken, and you eliminate the time-consuming process and costs associated
with developing the film. It is just important to note that you should shoot at a higher pixel count (which can be accomplished
by telling the camera to shoot a high- or best-quality mode). You can always crop or shrink the image down for output or display,
but you should avoid having to enlarge the image as this will create unwanted softness or pixelization (a visible blockiness)
in the image.

Shooting JPEG vs. RAW

When digital cameras became commercially available, the memory cards used to store pictures were very expensive. Photographers
could not afford multiple or high-capacity cards, so they wanted more images to fit on a single, smaller card. Many users
also emailed their pictures to friends and family. Smaller file size enabled consumers who lacked an understanding of digital
imaging to attach photos to email with minimum technical headaches. With these two scenarios in place, manufacturers turned
to an Internet-friendly format, JPEG. It was a proven technology and one that was familiar to many users.

The Joint Photographic Experts Group ( JPEG) format is extremely common as most hardware and software manufacturers have built
support for it into their products. The JPEG format is also extremely efficient at compressing images, and it is a good format
for continuous tone images, such as photos. A JPEG file looks for areas where pixel detail is repeated, such as the color
white on every key of your computer keyboard. The file can then discard repeated information and tell the computer to repeat
certain color values or data to re-create the image.

While JPEG is a good format for distributing images (due to their compatibility and small file size), it is not great for
image acquisition or production. A JPEG file is lossy, as every time you modify it in Photoshop, and resave, additional compression
is applied to the image. Over subsequent compressions, the image quality can noticeably deteriorate. This is similar to the
act of making a photocopy of another photocopy: Additional image deterioration occurs with each processing step. The visible
loss in image detail or accuracy is referred to as compression artifacts.

So, if JPEG is so bad, why do so many people use it? Money and resistance to change are the simple answers. It’s a lot cheaper
to shoot JPEG images, as you don’t need to buy as many memory cards. Additionally, even many pros have been slow to abandon
JPEGs. Learning how to use new technology requires time, something that most people are short of these days.

Newer digital cameras, generally the pro models, offer a newer format called raw. This newer format has several benefits over
shooting to JPEG. The images are usually captured at a higher bit rate, which means that the pixels contain more information
about the color values in the image. Most raw files have a depth of 12 bits (or 16 bits) per channel instead of the 8 used
by JPEG. This raw format also has a greater tonal range, hence better exposure for shadows and highlights. This extra information
will make your work in Photoshop easier as it adds greater flexibility and control in image adjustments and color correction. You
should have less work to do as well, since the image captured more detail than a JPEG would have.

Tip: Workaround for Unsupported Cameras

If Photoshop does not support a particular raw format used by your camera, then turn to the software that shipped with the
camera. The image can be converted into a TIFF image (a high-quality file with no compression), which Photoshop can open.

Raw files can be two to six times larger than JPEG files. This extra data is used to hold more image detail. This can reduce,
or even eliminate, compression artifacts. However, that extra data can take longer for the files to write to the memory card.

The raw file captures the unprocessed data from the camera’s image sensor. While your camera may contain settings for sharpness,
exposure, or lighting conditions, the raw file stores that info as modifiable information, and captures the original (unmodified)
data that came through your camera’s sensors. Each manufacturer treats the format differently, using a proprietary format.
Fortunately, Photoshop frequently updates its raw technology to support the newest cameras on the market. To find out if you
can access a particular camera format from within Photoshop, visit Adobe’s Web site (www.adobe.com/products/photoshop/cameraraw.html).

Because the raw data is unprocessed, you must essentially “develop” the image data inside of Photoshop. You’ll be presented
with several choices when opening a raw image. You can choose to adjust several options related to the image, as well as the
lens and lighting conditions. You can “tweak” the image after shooting it (as opposed to JPEG, which is limited to the settings
you had when shooting).

In 2004 Adobe released the Digital Negative Specification (DNG). The code and specifications have been made publicly available
so manufacturers can build in support to their products. The goal was to replace several proprietary raw file formats with
a universal format. Despite initial optimism, camera manufacturers have been very slow to adopt it (some even refusing). At
this point, DNG files are a useful way to archive raw files and attach additional metadata. You can find out more at Adobe’s
site at www.adobe.com/products/dng/main.html.

The raw dialog box has continued to evolve since it was first introduced as a purchased add-on to Photoshop 7. Subsequent
versions of Photoshop have continued to modify the user interface. To help you learn about these options, your safest bet
is to read the many entries in the Adobe Help Center. Fortunately, the Camera RAW dialog box is fairly intuitive, especially
once you understand the concepts of adjusting images. Once you have completed Chapter 10, “Color Correction,” you should feel much more confident using the options in the Camera RAW dialog box.

Acquiring Images from a Digital Camera

There are two major ways of downloading images from a digital camera. Which connection type you choose will depend upon your
work environment and budget for additional hardware.

Tip: Make Backup Copies

You may want to work with a copy of your transferred image, especially if you are just getting started in Photoshop. Many
users will duplicate a folder of images and work with those. Others will burn a copy of the original images to a CD or DVD
for backup. Preserving an original digital file is a good idea for future usage. If shooting raw, there is no need to duplicate
the raw file. The modifications to the image are stored in a separate sidecar file in the folder with your images.

The first method involves plugging the camera directly into the computer. Many cameras ship with a connecting cable (generally
USB). The advantage of this approach is that it doesn’t require an extra hardware purchase. The primary disadvantages of this
method are that it ties up the camera and it is hard on delicate ports built into the camera. If you break the USB port by
constantly plugging and unplugging a camera, it can lead to an expensive service bill. The data port is interconnected with
several other systems on the camera; a break at one end can result in problems in other areas.

A better option is to purchase a stand-alone memory card reader. There are many options available, so ask yourself a few questions
and choose wisely:

1.

Do you need only one card format, or do you need to read multiple formats?

2.

Is read-only enough, or do you want to be able to erase and reformat cards while they are in the reader?

3.

How fast do you want your files to transfer? Many card readers are USB 1, which can take a long time to transfer files. Look
for USB 2 or FireWire for faster data rates. Laptop users with a PC card slot can purchase an effective card adapter for fast
file transfers without tying up ports.

Note: Transferring Files

The actual transfer of files is handled natively by your computer’s operating system. You can use built-in tools (like iPhoto)
to transfer files, or manually copy them to a folder on your computer.